Breast prosthesis with biologically absorbable outer container

ABSTRACT

A newly developed breast prosthesis overcomes the tightness and contracture of the fibrous capsule which forms around the existing prosthesis. The unique construction of the new prosthesis causes the capsule to form at a predetermined, controlled distance from the surface thereof. This prosthesis is constructed with a first phase or outer temporary component and a second phase or inner permanent component. The inner component is a container or sac of a flexible, non-absorbable material filled with a fluid or gel filler material. The temporary outer component is an outer container or cover of a material which is absorbable under the conditions of use, and an inert filler material, preferably an absorbable, biologically acceptable liquid, e.g. saline solution, filling the space between the inner and outer components. The inner component is preferably of silicone rubber film and is filled with a silicone gel. The outer portion is in the form of a sheet, film or coating of a material which can be absorbed in the body after surgical implantation. Suitable materials are ones which will be absorbed by phagocytosis or hydrolysis or other processes or which can be rendered absorbable by physical or chemical or enzymatic treatment or the like, prior to, during, or after surgical implantation. These materials include natural, synthetic or semisynthetic materials proven useful for surgical sutures and materials such as reconstituted collagen, polylactic acid, polyglycolic acid, polyglactin 910, reconstituted vegetable protein, etc.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to new and useful improvements in a breastprosthesis suitable for implantation in a human breast forreconstructive or cosmetic purposes.

2. Brief Description of the Prior Art

Surgical reconstruction of human breasts as a result of injury or as aresult of partial or total mastectomy has been performed for many years.In recent years, surgical augmentation of breasts has particularlybecome common for cosmetic purposes in cases of breast hypoplasia. Overthe past 10-15 years, various surgical prostheses have been developedfor implantation in the human breast as a part of breast reconstructionor augmentation. Recently developed prostheses have been satisfactory insome cases but in a substantial number of other cases significantdegrees of capsular tightness or contracture has developed causingundesirable appearance associated with some pain and discomfort.

Surgical procedures for breast reconstruction are described in detail inthe medical literature, particularly in Journals dealing with plasticsurgery. Some of this literature describes prosthetic devices which arein common use. The recently published textbook RECONSTRUCTIVE PLASTICSURGERY, CONVERSE, 1980, pp. 3694-3704 gives a thorough review of thehistory of the development of breast prostheses and of the problemsinvolved. PLASTIC SURGERY, WILLIAM C. GRABB AND JAMES W. SMITH, 1979 isanother text giving a thorough treatment of this subject. Representativemedical journal references, listed somewhat in order of relevance andimportance, are: PLASTIC AND RECONSTRUCTIVE SURGERY, December 1976, pp.689-693; August 1972, pp. 107-113; November 1976, pp. 555-560; August1976, pp. 137-141; January 1980, pp. 30-33; November 1977, pp. 720-724;August 1979, pp. 151-155; July 1980, pp. 71-73; June 1977, pp. 849-850;March 1980, pp. 302-306; and AESTHETIC PLASTIC SURGERY, 1979, 3:339-341;1978, 2:435-441; and 1978, 2:217-234.

Most of the prior art on the physical structure of breast prostheses,however, is found in the patent literature, particularly the UnitedStates patents relating to that subject. The patent literature includesmany experimental and non-commercial prostheses as well as ones whichhave had substantial medical usage. The following patents represent asummary of the most pertinent patent art dealing with breast prostheses.

Cronin U.S. Pat. No. 3,293,663 discloses a breast prosthesis comprisinga flexible container filled with a soft gel and a corrugated fabricattached to one side of the container so that tissue can grow throughthe fabric to anchor the container to the chest wall. This patent isprobably the earliest example of a medically acceptable prosthesis whichhas been commercially produced for many years. However, as notedelsewhere, this prosthesis has been subsequently found to be the focalpoint of a serious problem, viz. the formation of a tight fibrouscapsule which contracts and causes the prosthesis to become hard andpainful.

Hartley U.S. Pat. No. 3,934,274 discloses a deflatable breast prosthesiscomprising a pair of bags or sacs, one inside the other, filled withliquid. The outer bag is provided with a flap valve through which fluidcan be added or removed to adjust the amount of fill. This patentillustrates an attempt to design a prosthesis which could overcome theproblem of capsular contracture. However, this prosthesis has been usedonly to a limited extent and the procedure for softening the prosthesisby removal of fluid through the flap valve has not proved to betechnically successful and has been largely abandoned.

A number of U.S. patents disclose various proposed breast prostheseswhich do not appear to have had general acceptance in the medicalliterature. These patents may possibly represent experimental deviceswhich have not been accepted for commercial development and usage by themanufacturers of such equipment.

A series of patents to Pangman, starting prior to the Cronin patent,disclose some designs for breast prostheses which do not seem to be incurrent use. Pangman U.S. Pat. No. 2,842,775 discloses a surgicallyimplantable breast prosthesis for use in surgical reconstruction havingan outer layer of sponge material and an inner sac filled with a fluid.Pangman U.S. Pat. No. 3,366,975 discloses a breast prosthesis with acore of plastic foam surrounded by a membrane impervious to fluids and,in turn, covered by a porous layer to which human tissue can adhere.Pangman U.S. Pat. No. 3,559,214 discloses a breast prosthesis forsurgical implantation which is hollow and filled with a soft fluid gelbut is subdivided into a plurality of compartments. Pangman U.S. Pat.No. 3,683,424 discloses a breast prosthesis for surgical implantationwhich has an elastic sac containing a foam core and a liquid in thepores thereof and having a tube for adjusting the extent of fill of theimplant.

Several U.S. patents disclose various prostheses having fluid or plasticfillers and, in some cases, having means for adjusting the size orextent of fill. These devices do not appear to be available from anycommercial source and are assumed to be experimental or prototypes, e.g.Boone U.S. Pat. Nos. 3,600,718; Mohl et al 3,663,968; Perras et al3,665,520; Perras 3,681,787; McGhan et al 3,852,832; Koneke et al3,852,833; Lynch 3,883,902; Sanders et al 3,919,724; and Lynch3,986,213.

Cresswall U.S. Pat. No. 4,035,850 discloses a method and apparatus forinsertion of a soft prosthesis through an incision into a human body.

In considering the prior art on breast prostheses, it is necessary tokeep in mind the difference between surgically implanted prostheses andexternal prosthetic devices. The patent literature has numerous examplesof external devices which have little or no relevance to surgicallyimplanted prostheses, e.g. Bernhardt U.S. Pat. Nos. 2,542,619; Kausch2,543,499; Freedman 2,636,182; and Mann 3,619,819.

SUMMARY OF THE INVENTION

One of the objects of this invention is to provide a surgical procedureutilizing a new and improved surgically implanted prosthesis foraugmentation or reconstruction of the human female breast which avoidstightness and contracture of the fibrous capsule formed around suchimplanted prostheses after surgical implantation.

Another object of the invention is to provide a new and improvedsurgically implanted prosthesis for augmentation or reconstruction of ahuman female breast including means for effecting encapsulation of theprosthesis only at some distance from the surface of the prosthesis andwithout contractive pressure thereon.

Another object of the invention is to provide a new and improvedprosthesis for surgical implantation in the female human breast forbreast reconstruction or augmentation which includes a permanent coreprosthesis of selected shape and formed of a non-absorbable material andan outer covering or coating which is temporary and is formed of amaterial which is absorbable under conditions of use and having an outersurface spaced at a selected and controlled distance from the core.

Still another object of the invention is to provide a new and improvedprosthesis for surgical implantation in the female human breast forbreast reconstruction or augmentation which includes a core prosthesisof selected shape and formed of a non-absorbable material and an outercovering formed of an absorbable material having an outer surface spacedat a selected and controlled distance from the core.

Still another object of the invention is to provide a new and improvedprosthesis for surgical implantation in the female human breast forbreast reconstruction or augmentation which includes a core prosthesisof selected shape and formed of a non-absorbable material and an outersac formed of a material which is absorbable under conditions of use.

Yet another object of the invention is to provide a new and improvedprosthesis for surgical implantation in the female human breast forbreast reconstruction or augmentation which includes a core prosthesisof selected shape enclosed in a non-absorbable material, an outer sacformed of a material which is absorbable under conditions of use and aninert filler material filling the space within the outer sac and aroundthe core.

Other objects of the invention will become apparent from time to timethroughout the specification and claims as hereinafter related.

These and other objectives of the invention are achieved by the novelbreast prosthesis which consists of an inner permanent core comprising acontainer or sac of a flexible, non-absorbable material filled with afluid or malleable filler material, an outer temporary container, sac,cover or coating of a flexible material which is absorbable or can berendered absorbable under conditions of use, and an inert fillermaterial, preferably an absorbable liquid, filling the space between theinner and outer containers. The inner core container is preferably ofsilicone rubber film and is filled with a silicone gel. Other fillerssuch as inert particulate material or sponge material could be used. Theinner core can also be a double lumen prosthesis of the type presentlyin use with a valve in the outer lumen. Or the inner core can be asingle lumen inflatable type also with a valve to adjust the amount offill. The outer container is of a material which is absorbable, e.g. bydissolution, phagocytosis, hydrolysis, etc., or which can be renderedabsorbable under conditions of use. Preferred materials for the outercontainer are ones which are presently in use in surgical sutures. Theseand other suitable materials include films, sheets or coatings orreconstituted collagen, polylactic acid, polyglycolic acid, polyglactin910, polyesters, reconstituted vegetable protein, amylose, amylosederivatives, cellulose derivatives, etc. The liquid filler may be salinesolution or the like.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial section through a female human breast showing aprior art type of prosthesis at or shortly after the time of surgicalimplantation.

FIG. 2 is a sectional view of the surgical implantation shown in FIG. 1at a later time after initial formation of a tissue encapsulation.

FIG. 3 is a sectional view similar to that shown in FIG. 2 illustratingthe condition of the prosthesis after full formation and contracture ofthe tissue encapsulation.

FIG. 4 is an isometric view of a breast prosthesis representing apreferred embodiment of this invention.

FIG. 5 is a sectional view taken on the line 5--5 of FIG. 4.

FIG. 5A is a fragmentary view in section similar to FIG. 5 showing analternate embodiment in which the outer lumen of the prosthesis does notoverlap the back wall of the inner core or permanent component of theprosthesis.

FIG. 6 is a sectional view of a breast similar to that shown in FIG. 1showing the prosthesis of FIG. 4 at the time of implantation.

FIG. 7 is a sectional view of the prosthesis as implanted in accordancewith FIG. 6 after formation of the tissue encapsulation.

FIG. 8 is a sectional view of the prosthesis as shown in FIG. 7 afterthe outer sac has been absorbed.

FIG. 9 is a sectional view, similar to that shown in FIG. 5, of anotherembodiment of the breast prosthesis of this invention.

FIG. 10 is a sectional view, similar to that shown in FIG. 6, of stillanother embodiment of the breast prosthesis of this invention.

FIG. 11 is a sectional view, similar to that shown in FIG. 5, of anembodiment in which the core or permanent part of the prosthesis is of adouble lumen construction.

FIG. 12 is a sectional view of a breast with the prosthesis of FIG. 11implanted therein.

FIG. 13 is a sectional view of a prosthesis similar to that of FIG. 11in which the connection of the absorbable outer component to the corecomponent is as shown in FIG. 5a.

ANALYSIS OF THE PROBLEM

Since the development of the first prosthesis used in breastaugmentation and reconstructive surgery, tightness and contracture ofthe fibrous capsule formed around the prosthesis have been seriousproblems. Studies show that 35%-40% of patients who undergo breastaugmentation develop significant degrees of capsular tightness orcontracture which in some cases causes pain and discomfort. Tightnessand capsular contracture have caused augmented or reconstructed breaststo have unnatural spherical appearance and to feel hard and undesirableto the touch and palpation. Consequently, the patients as well assurgeons have been less than happy with the results.

Various clinical and laboratory research has been conducted over thelast 10-15 years trying to find a solution to the problem. Althoughsignificant improvements have been accomplished in the quality of theprosthesis itself, the problem of capsular contraction has not changedappreciably. Several techniques and methods and newer prostheses havebeen designed and used in an attempt to improve and mitigate the problemof capsular contracture. These techniques have been generallyunsuccessful and have been either completely abandoned or used with lessenthusiasm. The problem continues to the present day, see any of therecent publications listed above. One of the attempts to solve thisproblem involved the use of double lumen prostheses which wereintroduced on the assumption that if capsular contracture occurred theresulting compression on the prosthesis could be relieved by reducingthe amount of fluid in the outer lumen. Reducing the fluid was designedto be done by means of a percutaneous hypodermic needle through a valvein the implanted prosthesis. Clinical experience, however, has shownthat this procedure is not practical and it has been largely abandoned.It should be noted, that even if this procedure could be used, it wouldcause the outer sac or bag to wrinkle and create an undesirableappearance for the augmented or reconstructed breast.

Another approach to the problem of capsular contracture has been the useof steroids either by direct instillation in the pocket for theimplanted prosthesis or by adding such steroids to the fluid in theouter lumen of an inflatable implanted prosthesis. It was thought thatthe steroids would gradually pass through the wall of the outer lumeninto the surrounding tissues and would suppress the formation of fibroustissue and consequently make tightness of the encapsulation less likelyto happen. It should be noted, however, that there is a substantialdifference of medical opinion as to whether steroids have any sucheffect at all. Also, a major problem with the use of steroids for thispurpose is atrophy and depigmentation of the skin. It is seen thereforthat there is a great deal of controversy surrounding the use ofsteroids and serious question as to their utility for this purpose.

Up to this date, the only available way to remedy the capsularcontracture has been by surgery. The operation, which is called surgicalcapsulotomy and capsulectomy, amounts to incising and removing thecontracted capsule and implant and inserting either the same or anotherimplant. This operation, of course, may have the same fate as theoriginal one and the same problem of capsular contracture may come aboutall over again.

The problem of capsular contracture can be understood more clearly byreference to FIGS. 1 and 2 of the drawings. In FIG. 1, there is shown adetail view in partial section of a human female breast 1 which has atypical prior-art-type breast prosthesis 2 implanted therein. Theprosthesis 2 is preferably a flexible container or sac 3 of a suitablethin walled or film material such as silicone rubber enclosing a core ofa soft or fluid or malleable material. Core 4 is preferably of asilicone gel or other suitable material which provides for malleabilityor plasticity and yet is not unduly soft.

When a foreign body is implanted in human or animal tissues, the tissuesform a fibrous capsule around the foreign body to protect thesurrounding tissues. The encapsulation is a defensive mechanism and issomewhat similar to the formation of scar tissue in the healing of awound or surgical incision. In FIG. 2 of the drawings, the condition ofthe implanted prosthesis 2 is seen after a period of time whenprosthesis 2 has first become encapsulated. The encapsulation isindicated at 5 and represents a fibrous tissue capsule as shownschematically in FIG. 2. Fibrous tissue capsule 5 completely enclosesthe implanted prosthesis 2 and contracts around prosthesis 2 to causethe prosthesis to be compressed tightly. The contracture of capsule 5around prosthesis 2 results in the prosthesis developing a feel of beingvery hard and rigid, and ultimately assumes a nearly spherical shape asillustrated in FIG. 3. The formation of this hard, encapsulatedprosthesis is a serious condition both from medical and estheticviewpoints. It is this condition which has been discussed above andwhich the prior art techniques have failed to cure.

The problem of capsular contracture is very complex. To find a solutionto this problem, a number of physiological and physiopathological factshave been considered.

It is well known that the formation of fibrous connective tissue as acapsule around an implant or around any foreign body is a naturalphenomenon. Such a capsule will form regardless of the physical orchemical structure of the foreign body. The normal tissues surroundingthe foreign body or implant are reactive toward the intruder and willlay down fibrous tissues which form the capsule. To date, there has beenno way to prevent the formation of the fibrous capsule around implantsor prostheses or other foreign bodies.

A fibrous capsule always forms around implants or prostheses or foreignbodies in an intimate fashion conforming to their respective shapes andcurvatures. The capsule tends to contract tightly around the foreignbody being encapsulated. The intimacy of fibrous tissue formation arounda foreign body, which by existing techniques is inevitable, is the keyfactor in the formation of a tightly contracted fibrous capsule. Oncethe capsule has formed, it is permanent. That is, it will not dissolveor disintegrate by itself or by the enzymes or natural fluids of thebody. Also, there is no physical or chemical agent presently availablethat can be used to alleviate the tightness of the capsule.

After careful consideration of the factors discussed above relating tothe nature of the process of formation of the fibrous capsule it wasconcluded that the only factor in the encapsulation process which can bealtered is in the relationship of the capsule to the implantedprosthesis. It was concluded that alteration of the position of thefibrous capsule realtive to the implanted prosthesis would prevent theformation of a tightly contracted capsule.

This invention, therefor, represents a newly designed technique,utilizing a prosthesis of novel construction, whereby the capsule isforced to form at a controlled distance from the implanted prosthesisrather than intimately close to it. This solves the problem completelysince there is enough leeway between the implanted prosthesis and thefibrous capsule so that the problem of tightness or contracture isavoided. This is the essence of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention consists of a two-phase breast prosthesis comprising aninner permanent core of biologically compatible, non-absorbable materialsurrounded by means to effect capsule formation at a selected andcontrolled distance therefrom and without contractive pressure thereonafter surgical implantation.

The first phase or outer segment is temporary and consists of a flexiblewalled container or bag of a material which is absorbable or can berendered absorbable under conditions of use. The second phase or innersegment is permanent and consists of a core which is smaller than andcontained in the outer bag or container. The inner core is preferably asmaller container or bag which is made of a non-absorable material, suchas a silicone rubber film, and contains a suitable filler, such as anormal saline solution or silicone gel or any other malleable or plasticor fluid material. The space surrounding the core inside the outer bagor container is preferably filled with a saline solution. The distancebetween the outer container and the inner core can be exactly designedat a controlled measurement and is effective to cause the formation ofthe fibrous capsule at the same distance from the permanent implantedprosthesis.

MATERIALS OF CONSTRUCTION

As noted above, the outer container or sac is a film or thin walledmaterial or coating which is absorbable under conditions of use or canbe rendered absorbable under conditions of use. An "absorbablematerial", as that term is used herein, is defined as any material whichis biologically acceptable and, under the conditions of use, can beabsorbed by the body tissues, i.e. dissolved or disintegrated andremoved by the body. This definition includes materials which arerecognized in the medical literature as being absorbable; materialswhich have known or readily determined properties permitting absorptionor dissolution by the body; and materials which can be treated at thetime of manufacture, or prior to, during, or subsequent to surgicalimplantation to render them capable of absorption or dissolution or thelike.

These materials may be absorbed by phagocytosis, enzymaticdecomposition, dissolution, hydrolysis, etc. under conditions existingnaturally in the body. Alternatively, materials can be used, which arewithin this definition of absorbable materials, which are absorbable byreason of chemical or physical treatment at the time of manufacture orprior to, during, or subsequent to surgical implantation. This wouldinclude materials which are not themselves absorbable but which are orbecome absorbable under conditions of use. Thus, regenerated celluloseis not itself absorbable but can be rendered absorbable by treatmentwith the enzyme cellulase. Similar enzymes, e.g. proteinase,collagenase, amylase, etc., are known which will decompose protein,collagen, and amylose materials. Also, some protein materials degenerateat certain conditions of pH. It is thus apparent that the outercontainer can be formed of materials which are not themselvesabsorbable, but which can be treated, as by addition of chemicals orenzymes to the materials or to the fluid inside or surrounding the outercontainer to render such materials absorbable. Materials which can berendered absorbable in this or similar manner are considered to bewithin the above definition of absorbable materials.

The initially preferred materials are ones which have had a longestablished use in surgery, particularly suture materials includingproperly processed and sterilized animal gut, collagenous materials, andsynthetic suture materials such as polyglycolic acid, polyglactin 910,reconstituted collagen, etc. Synthetic films which may be used includesynthetic protein film or sheet material made of reconstituted collagenor reconstituted animal or vegetable protein or the like. Othersynthetic absorbable materials which may be used include films ofabsorbable polyesters, such as condensation polymers of hydroxy-organicacids, e.g. polylactic acid, polyglycolic acid, polyglactin 910, etc.,and low molecular weight polyesters of glycols or other polyols anddibasic or polybasic acids, e.g. polyesters of succinic acid (succinicacid polyesters as bioabsorbable materials are described in Coquard etal U.S. Pat. No. 3,883,901).

In addition, films may be used which are of naturally occurringmaterials or derivatives thereof, which have a very low solubility inwater. Suitable films include starch films, amylose films, films ofcellulose derivatives, such as methyl cellulose, ethyl cellulose,hydroxyethyl cellulose, carboxymethyl cellulose, etc. In the case ofthese films of carbohydrates or carboydrate derivatives, it should benoted that the important characteristic required is that the film haveonly a very slight solubility in water. These materials are nontoxic andthe ones that are very slightly soluble in water will be dissolvedslowly and removed over a period of time. Similar materials can be usedwhich are not soluble or absorbable but which are rendered soluble orabsorbable by incorporation of a suitable chemical or enzyme or by afurther chemical or enzymatic or physical treatment.

MECHANISM OF FUNCTION OF INVENTION

When this two-phase prosthesis is implanted, the fibrous capsule willform around the phase one or outer temporary container which is at adistance from the core which represents the phase two or permanent partof the prothesis. Over a period of time, the outer bag or container willbe absorbed by the body leaving behind a fibrous capsule which is largerthan, and not intimately attached to, the inner core of nonabsorbableimplant. The distance between the formed capsule and the permanentprosthesis can be exactly predetermined at the time of construction bypositioning the outer absorbable layer at the optimum and desired spacefrom the inner non-absorbable permanent core. This will all be describedin more detail in connection with the several specific examples of theimproved breast prosthesis which is to be described below.

In FIG. 4 there is shown an isometric view of an improved,surgically-implantable breast prosthesis 12 which represents a preferredembodiment of the invention. In FIG. 5, breast prosthesis 12 is shown insectional view along a center line thereof to illustrate the two-phaseconstruction. Breast prosthesis 12 consits of an inner core 13 ofbiologically acceptable material. Core 13 is preferably a sac orcontainer 14 of a film or thin-walled flexible material, such assilicone rubber and is filled with a liquid or fluid or plasticsubstance 15. The filler material 15 is preferably a silicone gel or maybe a liquid, such as a sterile saline solution. Other malleable orplastic or semifluid materials may be used to fill the sac or container14 as long as they are sterile, nontoxic and of low density. The core 13of breast prosthesis 12 is enclosed in an outer sac or container 16 of athin-walled flexible material or film of a bioabsorbable material. Therear wall of core 13 may be completely covered by outer lumen or sac 16,as seen in FIG. 5, or the outer lumen or sac 16 may be sealed to theedge of the rear wall as indicated at 26 in FIG. 5A. In the embodimentof FIG. 5A, the exposed rear wall of core 13 may be provided with afabric patch or cover as in the prosthesis of Cronin. The space insidethe sac or container 16 and surrounding the core 13 is filled with asuitable biologically acceptable liquid or an absorbable sponge 17.

In the prosthesis, as shown and described in FIGS. 4, 5 and 5A, theouter container or sac 16 is of any suitable absorbable film or thinwalled material. Such absorbable material is a material as defined aboveand should be capable of preparation in a form which can be used insurgical implantation. The mechanism of absorption of the absorbablematerial depends upon the particular material used. Thus, gut andprotein or collagenous films are generally absorbed by phagocytosis.Polyesters and polymers such as polyglycolic acid, polylactic acid,polyglactin 910, etc. are absorbed by hydrolysis and dissolution of thehydrolysis products. Amylose and certain cellulose derivatives areabsorbable by slow dissolution. Other films, including cellulose andcertain protein films, can be absorbed by enzymatic attack or byphysical or chemical decomposition. In the case of materials which arerendered absorbable under conditions of use the enzymes or otherchemicals required can be added directly to the film material or can beincorporated into the fluid inside the outer container at the time ofmanufacture or at a later date (including introduction by hypodermicneedle after surgical implantation) or can be instilled in the surgicalcavity.

While the outer temporary sac or container 16 is of a nontoxicabsorbable material, the inner permanent core 13 is of a biologicallyacceptable or compatible non-absorbable material and is preferably a sac14, as previously described, of a biologically acceptable or compatiblefilm or covering or coating material, silicone rubber being a preferredmaterial. The filler material 15 within the core is preferably a gel orsemisolid, such as silicone gel or a liquid, such as a saline solutionor other similar material. The inner core could also be filled with apowdered or granular material 25 as shown in FIG. 10, all of the othercomponents being the same as shown in FIGS. 4 and 5. In such embodiment,the granular material would have to be a very low density material whichis sterile and nontoxic and biologically acceptable. A finely dividedcellulose or microspheres of glass or phenolic resin could be used forthis purpose. Another embodiment which would function satisfactorily, isshown in FIG. 9, in which the core 13 is of a sponge material 35 whichis biologically acceptable and which may be provided with or without theinner sac 14 covering the core. The remaining structure of theprosthesis shown in FIG. 9 is the same as shown and described in FIGS. 4and 5 and any of the defined materials of construction can be used.

In FIGS. 6 to 8 of the drawings, there is illustrated the results of theimplantation of the prosthesis of this invention in a human femalebreast. In FIG. 6, the prosthesis shown in FIGS. 4 and 5 (or theprosthesis of FIG. 9 or FIG. 10) is shown at the time of originalimplantation. Prosthesis 12 is shown in section and in the view shown inFIG. 6 is essentially the same section as is seen in FIG. 5. In thisview, it is seen that the prosthesis 12 is positioned in place withouter sac 16 surrounding inner core 13 and spaced therefrom by the fluidor saline solution or absorbable sponge 17. The sac or container 16 isof an absorbable material as described above and is in contact with thetissues of the breast in the cavity formed in preparation forinstallation of the prosthesis. In FIG. 7, there is shown a section ofthe same breast after the capsule has formed as described for FIG. 2. Inthis view, it is seen that the tissues forming capsule 5 form on thesurface of sac or container 16 which is of an absorbable material. Sacor container 16 is effective to cause the capsule 5 to form at asubstantial spacing from inner core 13 as determined by the fluid 17filling the space around the core 13 inside the outer sac 16. In FIG. 8,the section shown is similar to that in FIG. 7 but represents thecondition as it exists several months later. At this time, inner core 13occupies the same position as shown in FIG. 7. The outer tissue capsule5 is in substantially the same position as shown in FIG. 7 or may havecontracted slightly. The outer sac or container 16, however, hascompletely disappeared and has been absorbed into the body tissues. Thespace between capsule 5 and inner core 13 is occupied by fluid material17 which may be the residue of the solution contained within outer sacor container 16 prior to its biological absorption or may be body fluid.In either case, the outer capsule 5 forms a container or shell whichfits loosely around inner core 13 and the prosthesis does not have thetight, hard feel of a prosthesis which is tightly encapsulated as shownin FIG. 3.

In FIGS. 11-13, there are shown embodiments in which the inner permanentcore itself consists of a double lumen construction of a type currentlyin use. Both lumens 14 and 14a of this structure are made of anon-absorbable material such as silicone rubber. The inner lumen 14a isfilled with a liquid such as normal saline or a gel such as silicone gelas indicated at 15. The outer lumen 14 is filled with a compatiblesolution such as saline as indicated at 17a.

The entire double lumen structure is contained, covered or coated withan absorbable material 16 whose outer surface is at some predetermineddistance from the outer surface of the double lumen structure. The outercover 16 preferably contains a liquid such as normal saline as indicatedat 17. In FIG. 13, the same structure is shown except that the outercovering 16 does not cover the back of the core and is sealed thereto asindicated at 26. In FIG. 12, the prosthesis of FIG. 11 or 13 is shownimplanted in a female breast.

The advantage of this particular embodiment is that "bleeding" orleaking of silicone gel 15, if this material is used, from the innerlumen 14a will not come in contact with the fibrous capsule. Thereforefurther stimulation and thickening of the fibrous capsule by thesilicone gel molecules will not occur. Whatever leaking of the contentsof the inner lumen occurs will be trapped in the outer lumen of thedouble lumen structure and will not reach the fibrous capsule to causefurther thickening.

While this invention has been described fully and completely withspecial emphasis upon several preferred embodiments it should beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described herein.

I claim:
 1. A breast prosthesis comprising an inner core of biologicallycompatible, non-absorbable material, andbiologically absorbable meanssurrounding said core for effecting capsule formation at a selected andcontrolled distance from said core without contractive pressure thereonafter surgical implantation.
 2. A breast prosthesis according to claim 1in whichsaid means comprises a flexible wall covering or containersurrounding said inner core, said biologically absorbable flexible wallcovering or container at least at the time of surgical implantationhaving a biologically compatible liquid in the space between saidflexible wall covering or container and said core.
 3. A breastprosthesis comprisingan inner coherent core of biologically compatible,non-absorbable material and an outer covering of absorbable materialhaving an outer surface spaced from the surface of said core.
 4. Abreast prosthesis according to claim 2 in whichsaid absorbable materialis a material selected from the group consisting of materials which areabsorbed by hydrolysis, materials which are absorbed by phagocytosis,materials which are absorbed by enzymatic decomposition and materialswhich are absorbed by chemical or biological reactions.
 5. A breastprosthesis according to claim 3 in whichsaid absorbable material is amaterial which is formed in situ by reaction of an initiallynon-absorbable material with added chemicals or enzymes.
 6. A breastprosthesis according to claim 5 in whichsaid chemicals or enzymes areadded to said initially non-absorbable material at the time ofmanufacture.
 7. A breast prosthesis according to claim 5 in whichsaidchemicals or enzymes are added to said initially non-absorbable materialin admixture with fluid introduced inside said outer covering.
 8. Abreast prosthesis according to claim 7 in whichsaid chemicals or enzymesare added to said fluid after surgical implantation of said prosthesis.9. A breast prosthesis according to claim 5 in whichsaid chemicals orenzymes are added to said initially non-absorbable material at the timeof surgical implantation of said prosthesis.
 10. A breast prosthesisaccording to claim 3 in whichsaid absorbable material is a materialwhich is formed in situ by physical treatment of an initiallynon-absorbable material to render the same absorbable.
 11. A breastprosthesis according to claim 3 in whichsaid outer covering ofabsorbable material comprises an outer container of a flexibleabsorbable material spaced from said core, and an inert filler materialfilling the space between said outer container and said core.
 12. Abreast prosthesis according to claim 11 in whichsaid outer containercomprises a film of a natural or synthetic or semisynthetic absorbablematerial.
 13. A breast prosthesis according to claim 11 in whichsaidouter container comprises a film of a material selected from the groupconsisting of catgut, chromic gut, reconstituted animal collagen,reconstituted vegetable protein, absorbable carbohydrate polymers, andabsorbable synthetic or semisynthetic polymers.
 14. A breast prosthesisaccording to claim 13 in whichsaid film is an absorbable polyester of adibasic acid.
 15. A breast prosthesis according to claim 14 in whichsaidfilm is an absorbable condensation polymer of a hydroxycarboxylic acid.16. A breast prosthesis according to claim 15 in whichsaid polymer ispolyglycolic acid or polyglactin
 910. 17. A breast prosthesis accordingto claim 11 in whichsaid outer container comprises a film of anabsorbable polymer of cellulose or amylose or derivatives thereof.
 18. Abreast prosthesis according to claim 11 in whichsaid inert fillermaterial is a biologically compatible solution.
 19. A breast prosthesisaccording to claim 11 in whichsaid inner core comprises an innercontainer of a biologically compatible non-absorbable film enclosing aquantity of fluid material.
 20. A breast prosthesis according to claim19 in whichsaid fluid material in said inner container is a biologicallycompatible liquid.
 21. A breast prosthesis according to claim 19 inwhichsaid fluid material in said inner container is a gel material. 22.A breast prosthesis according to claim 19 in whichsaid inner corecomprises a container of silicone rubber film enclosing a quantity ofsilicone gel.
 23. A breast prosthesis according to claim 11 in whichsaidinner core comprises a non-absorbable sponge of a biologicallycompatible material.
 24. A breast prosthesis according to claim 11 inwhichsaid inner core comprises a sponge enclosed in a biologicallycompatible, non-absorbable film.
 25. A breast prosthesis according toclaim 3 in whichsaid outer covering comprises an absorbable sponge. 26.A breast prosthesis according to claim 3 in whichsaid inner corecomprises a double lumen prosthesis.